Wei Xiao-Xin, Wang Xiao-Quan
Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, 20 Nanxincun, Xiangshan, Beijing 100093, China.
Mol Ecol. 2004 Oct;13(10):3115-23. doi: 10.1111/j.1365-294X.2004.02299.x.
Gene paralogy frequently causes the conflict between gene tree and species tree, but sometimes the coexistence of a few paralogous copies could provide more markers for tracing the phylogeographical process of some organisms. In the present study, nrDNA ITS paralogues were cloned from all but one species of Larix, an Eocene genus having two sections, Larix and Multiserialis, with a huge circumboreal distribution and an Eastern Asia-Western North America disjunction, respectively. A total of 96 distinct clones, excluding five putative pseudogenes or recombinants, were obtained and used in the gene genealogy analysis. The clones from all Eurasian species of section Larix are mixed together, suggesting that recolonization and recent morphological differentiation could have played important roles in the evolution of this section. In contrast, the species diversification of the Eurasian section Multiserialis may result from radiation in the east Himalayas and its vicinity, considering extensive nrDNA founder effects in this group. Our study also suggests that the distribution pattern analysis of members of multiple gene family would be very useful in tracking the evolutionary history of some taxa with recent origin or rapid radiation that cannot be resolved by other molecular markers.
基因平行性常常导致基因树与物种树之间的冲突，但有时少数平行拷贝的共存可为追溯某些生物的系统地理学过程提供更多标记。在本研究中，从落叶松属除一个物种外的所有物种中克隆了nrDNA ITS平行物，落叶松属是一个始新世属，有两个组，即落叶松组和多脉落叶松组，分别具有巨大的环北极分布以及东亚 - 北美西部间断分布。共获得96个不同的克隆，排除5个推定的假基因或重组体后用于基因谱系分析。来自落叶松组所有欧亚物种的克隆混合在一起，这表明重新定殖和近期的形态分化可能在该组的进化中发挥了重要作用。相比之下，考虑到该组中广泛的nrDNA奠基者效应，多脉落叶松组欧亚物种的多样化可能源于东喜马拉雅及其附近地区的辐射。我们的研究还表明，多基因家族成员的分布模式分析对于追踪一些起源较近或辐射迅速、无法通过其他分子标记解决的分类群的进化历史非常有用。
